Acoustic device



1930. M. R. HUTCHISON 1,784,595

.ACOUSTIC DEVICE Filed Feb. 18. 1927 2 Sheets-Sheet 2 44 I 44 INVENTOR ATTORNEY Patented Dec. 9, 1930 UNITED STATES'PA-TENT DFFICE I MILLERREESE nuronrson, F LLEWELLYN PARK, WES'I' oRANennEw JERSEY, As-

srenon, BY erasure AssrenMENrs, r0 ACOUSTIC PRODUCTS corrrany, 0E NEWYORK, N. v n cenronarron or DELAWARE g ACOUSTIC nEvIcE Application filedFebruary 18, 1927. Serial no. 169,185,

This invention relates to acoustic devices for producing compressionalwaves of complex wave form.

The invention has for its principal object the faithful reproduction ofspeech and music from any surface.

In reproducing speech and music faithfully, it is, of course, essentialthat there shall be produced not only the fundamental tonescorresponding inpitch to that of the voice or musical note being"sounded, but also all of the useful upper harmonics whereby the timberand quality of the sound are recognized by the listener, and whereby afull appreciation may be obtained; and it isalso important that all ofthe fundamentals and overtones shall be reproduced in the sameproportions which were foundin the original.

Heretofore, the faithful reproduction of all the harmonics of speech andmusic has been attempted by a variety of expedients, in cludmg sheets ofpaper or parchment, as m the so-called cone type of loud speaker, thehorn type, in which a column of air is caused to resonate, and others.

Such expedients have,'however, not proven entirely successful or whollyfeasible. .For example, the cone speaker when made in sizes convenientfor ordinary use, as in the home, has not responded to a sufficientlywide range of vibration frequencies; and when made so to respond hasbeen too large for convenience. Furthermore, the horn type of loudspeaker, when made in ordinary sizes, produces the so-called barrelefiect, at once distracting and disagreeable.

Furthermore, prior types of loudspeakers do not operate satisfactorilyin all rooms, the

acoustics depending upon size, shape and furnishings. It is well known,for example,

that the same type of such prior instrument gives different results indifferent locations. My invention has for one'of its ob ects,

therefor, the use of'someobject to be found in i any room in whichreproduction of speech or music is to be efiected, and thus by theselection of an object havinga relatively large surface, the room can befilled with sound.

The selection of the object can readily be made so that a sufficientlylarge resonating sur- -Figures 1 and 2;

face isprovided to accommodate the room with sound, and effectively toobviate repress on or accentuation of'any band of frequencies. V

By thus employing anobject already forming a part of the room, theacoustics of the room are unchanged, and-since any suitable object,conforming in its resonating characteristics to what the listeners deemdesirable, can be selected, the most suitable effect can thus be readilyobtained. I The invention relates to an improved method of and means forimpressingu'ndulatoryenergy to an object.

According to this feature extremely large vibrating surfaces may readilybe employed for the reproduction of sound, without requiring the specialuse of a large cumbersome vibratory element.

According to another feature of the inven tion the device may beattachedin such manner as to bear against the surface to be vibratedwith considerable pressure, so asreffectively to prevent the vibratingelement of the device from .leavingthe surface, even during the extremesof its vibration. 1

Another feature relates to stressing the ma terial of the object to bevibrated, thereby assisting considerably in the faithful reproduction ofsound.

Other objects will'appear from the followingdescription and claims takenin connection with the accompanying drawings in which Figure 1 is a sideelevation of one form of device embodying features of the invention;Figure 2 is a plan view of the device of Figure 1;

' Figure 3 is an endxview from the left of Figure 4 is a detail viewpartly in section of a portion of Figure 3 with the actuating element indisplaced position; and

Figure 5 is a modified form of the structure shown in Figure 1.

Like reference characters refer to like parts in the several-figures ofthe drawings.

In the following description and claims,

parts, characteristic features and functions will beidentified byspecific names for convenience of expression, but they are intended tobe as generic in their application to similar parts or equivalentconstruction as the art will permit.

Referring to the form of the invention illustrated in Figures 1 and 2,there is provided a relatively massive element 10 which may preferablytake the form of a horse shoe magnet having one pole designated N andopposed pole designated S. The magnet 10 is sufficiently large so thatit has a large moment of inertia, at least with respect to theperiodicity of the waves which are to be received, so that it remainsinert with respect thereto. There is mounted on the continuous faces ofthe poles of the magnet 10 a pairof soft iron plates 11, 12respectively, each'of which is in magnetic contact with its respectivemagnet pole, being held in position by suitable screws such as 13.Positioned on the plate 11 of one .pole N is a pair-of cores, preferablylaminated, shown as at 14, 15, and held in place by clamps 16, 16..Mounted on the core 14 is an electro-magnet 17, and similarly mountedon the'core 15 is an electro-magnet 18, the magnets 17, 18 beingconnected in series by a conductor 19. The magnets 17, 18 are understoodto be connected by means of binding posts 50, in circuit with a sourceof undulatory energy of-complex wave form, such as a radio receivingset, an amplifier, a public address system, a phonographic pick-upsystemga telephone line or other desired device,

but as such devices form no part ofthe present invention it is thoughtthat a description thereof need not beincludecl herein; A return yoke20, preferably formed of laminated para-magnetic materialis provided forconnecting the outer ends of the cores 14,15,

thus forming a magnet circuit of efiicient type. The contiguous endsof'cores 14, 15 are spaced apart sufficiently so that the free end a ofa movable armature or vibrating element 21 may loosely extendthere-between.

For supporting the armature 21 there is mounted on the plate 12 of theother pole S a block 30 formed of para-magnetic material and having atits outer end a pair of spaced lugs or ears 31, 32, between which thereextends a flat spring plate 33 formed of slightly yielding material. Thearmature 21 is secured to an intermediate portion of the spring plate33, which thus forms effectively a pivotal mounting for the armaturewhich thus may be controlled in its movement by the energization of theelectromagnets 17 18. The plates 11, 12 are interconnected at their endsby magnetically inert braces 34, for maintaining the parts in relativelyfixed relation. The arrangement is such that the armature 21 is operatedupon by the magnets 17, 18 in push-pull fashion, i. e., when one of themagnets is energized to attract the free end of the armature, the othermagnet repels it and vice versa. The tension of the spring plate 33 issufficiently great to exert a considerable torque on the armature 21 ina counter clockwise direction as seen in Figure 3.

For supporting the electroresponsive device which has just beendescribed, there is provided in the embodiment shown in Figure 1 acurved bracket 40 formed of a yielding material which is magneticallyinert. The element 40 is connected at one end as by machine screws 41 toa block 42 formed of magnetically inert material. The block 42 issecured to the permanent magnet 10 as by screws such as 43 extendingtherethrough. The other 'end of the supporting means 40 is provided withspaced pads 44 and may be additionally fastened by means of aconventional wood screw 45 to an object 46 which is to be vibrated andwhich forms the vibratory element. The pads are preferably formed of asoft material such as soft rubber, to form suction pads,to protect thesurface of the object 46. A projecting arm operatively interconnectingthe armature 21 to the object 46 comprises a substantially rigid rod47,one end the end of the connecting rod 57 contacts at 49 with the surfaceof .the object 46, and the armature 21 isthus forced, againstthe'tension of the spring 33, into the position between the pole pieces,as illustrated in Fig.3.

The tension of the spring plate 33' is sufli ciently great to maintainthe end 49 of the rod 47 in intimate "contact with the object 46 at alltimes, even when energy of maximum intensity is impressedupon thedevice.

In the modified form of the invention shown in Figure 5, the springbracket 40 is made sufficiently extensive to bring the points of supportin proximity to an edge 50 of the object 46 so as to promote relativelyfree vibration of the middle portion of the object;

It will thus be seen that the device may be applied to any object to bevibrated, without undue harm thereto. For example, the device may bereadily attached to the sounding board of a piano and when thusemployed? produces excellent results. I have also found that almost anyobject such as a pane of glass, a table, a door, the floor, etc servesas an excellent vibratory element, when the device is used as has beenherein described.

What is claimed is: i 1. A device for vibrating an object inclu ding,-incombination, a vibrating element and electrical means for vibrating thesame in response to electrical waves of sound frequency, said vibratingelement being adapted to vibrate about a mean position, an arm attachedto said vibrating element, resilient means for holding said vibratingelement displaced from its mean position to cause the projection of saidarm, a support for all of said devices adapted to rest upon the surfaceto be vibrated, said projecting arm being adapted to project beyond saidsurface by an amount equal to the displacement of said vibrating elementfrom its mean position.

2. A device for vibrating an object, including, in combination, apermanent magnet, a vibrating element connected to one of the polesthereof, a pair of pole pieces connected to the other pole thereof, andelectrical means for magnetizing them in opposition to each other, saidvibrating element being adapted to vibrate between said poles, an armconnected to said vibrating element, means for supporting all of saidparts from the surface to be vibrated, resilient means for displacingthe vibrating element from its mean position between said pole pieces ina direction to project said arm below the surface of support by anamount equal to said displacement.

3. A device of the character described including, in combination, apermanent magnet, a vibrating element connected to one of the polesthereof, a pair of pole pieces connected to the other pole thereof, andelectrical means for magnetizing them in opposition to each other, saidvibrating element being adapted to vibrate between said poles, an armconnected to said vibrating element, means for supporting all of saidparts from a surface, resilient means for displacing the vibratingelement from its mean position between said pole pieces in a directionto project said arm below the surface of support by an amount equal tosaid displacement, said supporting means including suction cups adaptedto attach said element without marring the surface.

Signed at New York, in the county of New York and State of New York,this 17th day of February, A. D. 1927.

MILLER REESE HUTCHISON.

